The food and beverage industries as well as other industries such as the perfume, cosmetic and health care industries routinely use terpenes and/or terpenoid products as flavours and fragrances. By way of example, many sesquiterpene compounds are used in perfumery (e.g., patchoulol) and in the flavour industry (e.g., nootkatone) and many are extracted from plants. However, factors such as: (i) the availability and high price of the plant raw material; (ii) the relatively low terpene content in plant; and (iii) the tedious and inefficient extraction processes to produce sufficient quantities of terpene products on an industrial scale all have stimulated research on the biosynthesis of terpenes using plant-independent systems. Consequently, effort has been expended in developing technologies to engineer microorganisms for converting renewable resources such as glucose into terpenoid products. By comparison with traditional methods, microorganisms have the advantage of fast growth without the need for land to sustain development.
Many microorganisms use either the methylerythritol 4-phosphate (MEP) pathway or the melavonate (MVA) pathway to supply intermediates necessary to produce terpenoid products. These MEP or MVA pathways can include an endogenous or an engineered MEP or MVA pathway or both. A detailed understanding of isoprenoid pathway engineering and optimization is disclosed in WO 2011/060057, US 2011/0189717, US 2012/107893, U.S. Pat. No. 8,512,988 and Ajikumar et al (2010) Science 330 70-74, which discloses the production of various terpenoid compounds including sesquiterpene compounds such as nootkatone, which is an oxidised sesquiterpene produced from a valencene sesquiterpene substrate.
Nootkatone (4,4a,5,6,7,8-hexahydro-6-isopropenyl-4,4a-dimethyl-2(3II)-naphtalenone) is an important flavour constituent of grapefruit and is used commercially to flavour soft drinks and other beverages, as well as being used in perfumery. The conventional method for nootkatone preparation is by oxidation of valencene (see, e.g., U.S. Pat. Nos. 6,200,786 and 8,097,442). The starting material valencene is expensive and thus methods that consume valencene are less commercially acceptable. Because of these drawbacks, there is a need for commercially feasible and sustainable methods to prepare nootkatone and associated products.